72 blazer rear driveshaft u-joints?

[Madtrucker]

I just got my first 1st gen blazer but it's got a bad case of vibes. The joints are clunking in the driveshaft when going in gear so I'll start there. The question is are there other listed years that use the same joints? I've checked all the local parts stores and nobody has them listed. Is there an over the counter spicer I can buy? The spid shows my truck was a 307 standard trans, now it's a 350 auto. I'm also wondering if the stock driveshaft would've been changed.